1. Field of the Invention
This invention relates, generally, to metal-enclosed switchgear and more particularly to a stab-positioning system for the primary disconnect contact system and current conductors of metal-enclosed switchgear having removable draw-out circuit breaker units.
2. Description of the Prior Art
Whenever a draw-out circuit breaker device is utilized, the maintenance, testing and installation require that the circuit breaker be pulled out from or put back into a metal-enclosed switchgear housing. This requires the making and breaking of contact between the circuit breaker mechanism itself and current carrying conductors in the switchgear metal-enclosed housing. Generally, the circuit breaker apparatus will have a cluster arrangement having resilient fingers which move in conjunction with the circuit breaker itself making and breaking contact with fixed conductors, which are generally referred to as stabs and are insulated from and rigidly attached to the switchgear metal-enclosed housing. Such a scheme is taught in U.S. Pat. No. 4,002,865, "Draw-Out Type Circuit Interrupter With Interlocked Levering Mechanism", issued Jan. 11, 1977, to Kuhn et al; U.S. Pat. No. 4,002,864, "Enclosed Circuit Interrupter With Interlocked Safety Barrier", issued Jan. 11, 1977, to Kuhn et al; U.S. Pat. No. 3,562,593, "Metal-Enclosed Switchgear With Vertically Disposed Conductors", issued Feb. 9, 1971, to Bould, all assigned to the assignee of the present invention. These, as well as other types of draw-out switchgear require precise positioning of the stab unit so that no voltage drop or excess heat is produced at the point of electrical contact between the cluster and stab connection. This requires alignment of the stabs during the construction, maintenance and testing aspects of the circuit breaker. Therefore, some stab alignment schemes utilize extensive and complicated arrangements to ensure proper stab alignment.
It is desirable to have a stab which is easier to position in the switchgear enclosure, provides precise alignment and requires less attention at the time of manufacture, test, maintenance and replacement. It is also desirable to have a stab arrangement which is less complex and requires fewer parts. Such a scheme is taught in the present invention.